A short pulse fiber laser amplification system includes a special fiber stretcher, managed preamplifier, managed amplifier chain, and managed compressor to control an increase of a passive dispersion by managing a third order dispersion (TOD) to a group velocity dispersion (GVD) ratio for matching a nonlinearity chirp. In an exemplary embodiment, the TOD to GVD ratio is managed between approximately 1.5 to 15 fs to match a nonlinearity in range between 1π to 10π. In another exemplary embodiment, the TOD to GVD ratio is managed between approximately 15 to 705 fs to match a nonlinearity in range between 1π to 50π.
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1. A short pulse fiber laser amplification system comprising:
a fiber stretcher comprising a fiber of a flat or negative third order dispersion (TOD) (a dispersion slope or a slope of dispersion versus wavelength);
a managed preamplifier;
a managed amplifier chain; and
a managed compressor;
the short pulse fiber laser amplification system being configured to:
control an increase of a passive dispersion by managing a third order dispersion (TOD) to group velocity dispersion (GVD) ratio for matching a nonlinearity chirp; and
maintain compressibility of a laser pulse passing through each component of the short pulse fiber laser amplification system.
8. A method for reducing a passive dispersion in a short pulse fiber laser amplification system comprising:
managing a third order dispersion (TOD) to group velocity dispersion (GVD) ratio, wherein managing the TOD to GVD ratio comprises:
matching a nonlinearity chirp by implementing a fiber stretcher comprising a fiber of a flat or negative TOD (a dispersion slope or a slope of dispersion versus wavelength), a managed preamplifier, a managed amplifier chain, and a managed compressor in said short pulse fiber laser amplification system; and
maintaining compressibility of a laser pulse passing through each component of the short pulse fiber laser amplification system.
2. The short pulse fiber laser amplification system of
3. The short pulse fiber laser amplification system of
4. The short pulse fiber laser amplification system of
a special grating pair designed to control the dispersion and the nonlinearity chirp.
5. The short pulse fiber laser amplification system of
6. The short pulse fiber laser amplification system of
7. The short pulse fiber laser amplification system of
9. The method of
10. The method of
11. The method of
implementing a special grating pair in said fiber stretcher to control said dispersion and said nonlinearity chirp.
12. The method of
13. The method of
14. The method of
15. The short pulse fiber laser amplification system of
16. The method of
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This Formal Application claims a Priority Date of May 18, 2006 benefit from a Provisional Patent Applications 60/801,267 filed by the same Inventor of this Application. The disclosures made in 60/801,267 are hereby incorporated by reference in this Patent Application.
The present invention relates generally to apparatuses and methods for providing fiber laser system. More particularly, this invention relates a system configuration implemented with pulse shaping by managing non-linearity and dispersion that accumulate inside the fiber laser amplifier system to control the pulse reshaping dynamics and obtain the optimized pulse shape in the high energy short pulse fiber amplifier.
Even though current technologies of fiber laser have made significant progress toward achieving a compact and reliable fiber laser system providing high quality output laser with ever increasing output energy, however those of ordinary skill in the art are still confronted with technical limitations and difficulties. Specifically, in a fiber laser system implemented with the Chirped Pulse Amplification (CPA) for short pulse high power laser amplifier, the non-linearity comes up naturally with the short pulse fiber laser. Due to the fact that the non-linearity effects are inherent with the short pulse laser fiber, and the removal of such non-linearity appears to be impossible, the bottom line problem is not to try to eliminate the non-linearity. Rather, the major thrust of research efforts now is directed toward a solution in finding a method to manage the non-linearity.
For a fiber laser system, the phenomenon of laser dispersion in a fiber laser system is confronted with the same difficulties with the same situation. The dispersion is inherently generated during the transmission and amplification of the laser in the fiber laser system. Furthermore, it is also practically impossible to remove the dispersion from a fiber laser system. Therefore, the key and the central idea is not to eliminate the nonlinearity and dispersions but to obtain the best pulse shape as that is necessary to control the nonlinearity and dispersion in the whole fiber amplifier system. However, the conventional technologies for configuring a high energy, short pulse fiber laser system have not yet provided a solution to effectively manage and resolve such difficulties.
In a high-energy short-pulse fiber laser system, the generation of dispersion is more than a passive effect. In the fiber laser system, besides the polarization mode dispersion (PMD), the material and waveguide dispersion are two main passive sources, which will affect the pulse shaping dynamics. The passive dispersion can be classified according to the mathematical expression and relevant importance for the pulse reshaping dynamics, as the group velocity dispersion (GVD) and the third order dispersion (TOD). The GVD and the TOD are introduced by the fiber components. A conventional single mode fiber stretcher may accumulate very high passive dispersion, including GVD and TOD and the pulse duration is then largely stretched accordingly. The stretched pulse is partly compressible without further amplification.
On the other hand, the nonlinearity not only generates more spectra via SPM and Stimulated Raman Scattering (SRS) thus inducing self-focusing under extreme peak power, the nonlinearity can also introduce drastically large chirp into the pulse. The large chirp might change the pulse shaping process permanently that is generally referred to as the nonlinearity chirp. Comparing with the passive dispersions, the nonlinearity chirp has different evolution dynamics and functionality for the pulse reshaping process. The pulse reshaping can be constructive or destructive and the pulse can be re-compressible, or it could be unable to get re-compressed. Conventional laser fiber systems still have limitations to assure that the laser transmitted in the system can be continuously maintained as a re-compressible pulse.
For a CPA fiber system shown in
Therefore, a need still exists in the art of fiber laser design and manufacture to provide a new and improved configuration and method to provide fiber laser to manage the nonlinearity and the dispersion generated in the laser system such that the above-discussed difficulty may be resolved. Specifically, since the nonlinearity and the dispersion phenomena are encountered in the entire fiber system, it is further desirable to provide new and improved system configurations and method to manage the nonlinearity and the dispersion over the entire fiber system and over both high and low levels of laser energies to achieve even further improvements for even boarder scopes of applications.
It is therefore an aspect of the present invention to provide a short pulse fiber laser amplification system by implementing a special fiber stretcher, managed preamplifier, managed amplifier chain, and managed compressor to control the increase of the passive dispersion. The control of the passive dispersion is achieved by managing the ratio of the higher order dispersion such as the TOD to the GVD to match the nonlinearity chirp such that the above-discussed difficulties as that encountered in the prior art may be resolved.
Specifically, it is an aspect of the present invention that a high-energy short pulse fiber laser system is implemented to achieve for the TOD/GVD between 1.5 fs to 15 fs, to match the nonlinearity in the range of 1π to 10π. On the other hand, the nonlinearity of 10π to 50π is matched with a corresponding TOD/GVD of 15 fs to 75 fs.
Another aspect of this invention is to implement a high-energy short pulse fiber laser system to control the passive dispersion in the system by implementing special stretcher and special grating pair is designed to control the dispersion and to compensate the nonlinearity chirp.
Briefly, in a preferred embodiment, the present invention discloses short pulse fiber laser amplification system that includes a special fiber stretcher, managed preamplifier, managed amplifier chain, and managed compressor to control an increase of a passive dispersion by managing a third order dispersion (TOD) to a group velocity dispersion (GVD) ratio for matching a nonlinearity chirp. In an exemplary embodiment, the TOD to GVD ratio is managed between approximately 1.5 to 15 fs to match a nonlinearity in range between 1π to 10π. In another exemplary embodiment, the TOD to GVD ratio is managed between approximately 15 to 75 fs to match a nonlinearity in range between 10π to 50π. In another exemplary embodiment, the fiber laser system further includes a special grating pair designed to control a dispersion and a nonlinearity chirp. In another exemplary embodiment, the special stretcher further includes a dispersion managed fiber stretcher in order to compensate a TOD (dispersion slope, or a slope of dispersion versus wavelength) of a grating compressor or in a regular fiber. In another exemplary embodiment, the dispersion managed fiber stretcher includes fibers having a refractive index profile different from a conventional fiber. In another exemplary embodiment, the dispersion managed fiber stretcher includes fibers having reflection index profile different from a conventional fiber with a depressed cladding structure. In another exemplary embodiment, the dispersion managed fiber stretcher includes a fiber of a flat dispersion. In another exemplary embodiment, the dispersion managed fiber stretcher includes a fiber of a negative TOD (dispersion slope, or a slope of dispersion versus wavelength).
This invention further discloses a method for reducing a passive dispersion in a short pulse fiber laser amplification system. The method includes a step of managing a third order dispersion (TOD) to a group velocity dispersion (GVD) ratio for matching a nonlinearity chirp by implementing a special fiber stretcher, managed preamplifier, managed amplifier chain, and managed compressor in the laser fiber system to reducing the increase of a passive dispersion. In an exemplary embodiment, the step of managing the TOD to GVD ratio further includes a step of managing the TOD to GVD ratio between approximately 1.5 to 15 fs to match a nonlinearity in range between 1π to 10π. In another exemplary embodiment, the step of managing the TOD to GVD ratio further includes a step of managing the TOD to GVD ratio between approximately 15 to 75 fs to match a nonlinearity in range between 10π to 50π. In another exemplary embodiment, the method further includes a step of implementing a special grating pair in the special stretcher to control a dispersion and a nonlinearity chirp. In another exemplary embodiment, the step of implementing the special stretcher further includes a step of implementing a dispersion managed fiber stretcher in order to compensate a TOD (dispersion slope, or a slope of dispersion versus wavelength) of a grating compressor or in a regular fiber. In another exemplary embodiment, the step of implementing the dispersion managed fiber stretcher further includes a step of implementing fibers having a refractive index profile different from a conventional fiber. In another exemplary embodiment, the step of implementing the dispersion managed fiber stretcher further includes a step of implementing fibers having a refractive index profile different from a conventional fiber with a depressed cladding structure. In another exemplary embodiment, the step of implementing the dispersion managed fiber stretcher further includes a step of implementing the dispersion managed fiber stretcher includes a fiber of a flat dispersion. In another exemplary embodiment, the step of implementing the dispersion managed fiber stretcher further includes a step of implementing a fiber of a negative TOD (dispersion slope, or a slope of dispersion versus wavelength).
These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment, which is illustrated in the various drawing figures.
In the fiber CPA laser system shown in
In general, it is extremely important to verify that the laser transmission in the fiber laser system always has a compressible amplification in the whole process of transmission through the entire fiber CPA system. The pulse reshaping due to the nonlinear phase shift and dispersion should be controlled during the whole amplification system to help the pulse compression instead of damage the compressibility. In the fiber CPA laser system, it is necessary to modify almost every single unit to ensure the compressibility despite of the increase of nonlinearity and dispersion. To fulfill these requirements, analyses are performed to calculate the dispersion increase for some important units.
In the modeling analyses of the fiber CPA laser amplifier, the increase of the nonlinearity, in terms of the B integral is also calculated as shown in
As a conclusion, the increase of passive dispersion in the short pulse high-energy amplifier is under control with the management of the ratio of high order dispersion, i.e., the TOD, to the GVD to match the nonlinearity chirp. In practice, for TOD/GVD between 1.5 fs to 15 fs, the nonlinearity should be in the range of 1π to 10π. On the other hand, the nonlinearity of 10π to 50π is corresponding to TOD/GVD of 15 fs to 75 fs. Furthermore, special stretcher and special grating pair are designed to control the dispersion and to compensate the nonlinearity chirp.
Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting. Various alternations and modifications will no doubt become apparent to those skilled in the art after reading the above disclosure. Accordingly, it is intended that the appended claims be interpreted as covering all alternations and modifications as fall within the true spirit and scope of the invention.
Patent | Priority | Assignee | Title |
8861075, | Mar 05 2009 | BOARD OF TRUSTEES OF MICHIGAN STATE UNIVERSITY | Laser amplification system |
Patent | Priority | Assignee | Title |
6307985, | Jul 10 1998 | Micro Therapeutics, Inc. | Optical transmission system |
20050105865, | |||
20060120418, | |||
20060232847, | |||
20070098025, | |||
EP971495, | |||
WO2006113507, |
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